Sion member method for obtaining a connection between a sheet member and a suspen

ABSTRACT

To obtain a connection between a foldable sheet material member and a suspension or stiffening member said sheet material member is first provided with a longitudinal bead having a wider upper portion and a narrower lower portion, whereupon the bead is sideways introduced in a corresponding downwardly open groove in the suspension or stiffening member. The bead is made by folding the sheet material along a plurality of folding lines, located in near vicinity to each other, at least some of said folding lines being made by punching in the sheet material a plurality of elongated slots, leaving between two adjacent slots a relatively long unpunched portion thus obtaining an easily foldable fold, difficult to tear. By varying the foldability of the folds for example by varying the length of the slots complicated foldings may be easily obtained in automatic processes.

United States Patent 1 Grundell METHOD FOR OBTAINING A CONNECTION BETWEEN A SHEET MEMBER AND A SUSPENSION MEMBER [76] Inventor: Carl Erik Grundell, 8 Osmagatan 122 48, Enskede, Sweden 22 Filed: May 5,1972

21 Appl. No.: 250,797

[ July 31, 1973 Primary Examiner-Andrew R. .luhasz Assistant ExaminerJames F. Coan Attorney-Linton & Linton [57] ABSTRACT To obtain a connection between a foldable sheet material member and a suspension or stiffening member said sheet material member is first provided with a longitudinal bead having a wider upper portion and a narrower lower portion, whereupon the bead is sideways introduced in a corresponding downwardly open groove in the suspension or stiffening member. The bead is made by folding the sheet material along a plurality of folding lines, located in near vicinity to each other, at least some of said folding lines being made by punching in the sheet material a plurality of elongated slots, leaving between two adjacent slots a relatively long unpunched portion thus obtaining an easily foldable fold, difficult to tear. By varying the foldability of the folds for example by varying the length of the slots complicated foldings may be easily obtained in automatic processes.

7 Claims, 4 Drawing Figures METHOD FOR OBTAINING A CONNECTION BETWEEN A SHEET MEMBER AND A SUSPENSION MEMBER DESCRIPTION:

In the manufacturing of for instance files for documents a sheet material member has to be connected to a suspension or stiffening member such as a rail. It is of great importance that such connections are reliable and sturdy and may be made in an economic way. To this end it has been suggested to provide in the sheet material member a bead, constituted by folding the sheet material along a plurality of folding lines, being located .in near vicinity to each other. The folding occurs along notches or indentations. It is however not possible to obtain with such a technique folds, being located very near to each other especially when a relatively thick sheet material is used. Owing to this fact the beads obtained will be quite wide which as regards files for documents is objectionable from the view of space requirements. Another disadvantage is that it is difficult to arrange the tools for making the indentations in such a manner that the folding lines will be fully parallel. A lack of parallelity leads to serious inconveniences in that the bead, which is usually sideways introduced into a groove in the suspension or stiffening member,

will stick in said groove as the tolerances between the bead and the groove limiting walls must be very close. It may also happen that a portion of the bead will be so narrow that it may leave said groove.

Another disadvantage is that providing longitudinal indentations near to each other and folding the material along said indentations causes material strains which in turn may cause breakage.

The main object of the invention is to overcome theese and other disadvantages, connected with methods according to the prior art and to provide a connection which is economical in manufacturing space saving, strong and reliable.

To achieve these objects the method now described is used. Reference is made to the accompanying drawing in which FIG. 1.is a plan view of a sheet material blank, provided with perforated folding lines FIG. 2 is an end perspective view of a first embodiment of the invention, the sheet material member having a substantially T-shaped bead being introduced in a corresponding longitudinal groove in the suspension or stiffening member FIG. 3 is a view similar to that of FIG. 2 but illustrating a second embodiment in which the head as well as the groove for receiving the same has a substantially triangular shape FIG. 4 illustrates in an end perspective view a third embodiment of the invention, there being two sheet material member parts, each having a substantially T- shaped head.

The sheet material member, generally designated 1, is provided with a number of perforated folding lines. These are made by punching through the sheet material a plurality of elongated slots 2, being spaced from each other in the direction of the intended folding lines. The space 3 respectively 4 between two adjacent slots is relatively wide, for example 2 3 mm for a sheet material thickness in the range 0.3 0,5 thereby giving the possibility of obtaining sharp bends at the same time as the member maintains its resistivity against tearing. By

varying the length of the spaces 3 respectively 4 from one folding line to another it is possible to obtain in an easy manner a differentiated folding tendency. When for instance as shown in FIG. 1 the two inner folding lines are made with shorter spaces 3 between the slots than the two outer folds the sheet member 1 will when the member is merely buckled first automatically form folds along said inner folding lines thus giving the member a U-shaped configuration. By only exerting a pressure against the web portion of said U or by pressing in the legs of said U-shaped portion the material will be folded along the outer folding lines thus giving the substantial T-shape shown in FIG. 2. This is of greatest importance as it makes it possible to carry out very complieated foldings in an easy manner, well suited for mass production. It is obvious that the folding lines here described may alternate with indentations of the known art, and that the length and width of the slots as well as the punching directions may also be varied, thereby giving the same result as mentioned above, i.e., a tendency of the sheet material to be first folded along the folding lines which offer the least resistance against such folding.

The bead, thus obtained, is thereupon sideways slid into a corresponding groove 5 adapted in a supporting rail 6, preferably made from plastic material in an extrusion process. Said groove 5 opens downwardly by means of a longitudinal groove 7. It is to be noted that the tolerance between the bead and the groove is very close so that the bead is protected against tearing and other kind of damages. The embodiment shown in FIG. 3 differs from that of FIG. 2 in that the bead has a triangular shape one of its sides comprising two superimposed layers of the sheet material. In this manner said second layer locks the bead thus constituting a very rigid bead construction. Of course the groove in the rail is then correspondingly shaped. As shown in FIG. 4 it is also possible to connect two ends of one or two sheet members to a rail by making in each a fold 8 thereupon assembling the folds as clearly shown. It is also possible to vary in one folding line the length of the unpunched portion. For instance by arranging at the ends of a fold relatively long unpunched portions the bead obtained is very resistent and easy to introduce in the groove of the suspension element.

Claims:

1. A method for obtaining a connection between a sheet member, made from a relatively stiff material such as cardboard or the like, and a suspension or stiffening member, said sheet member being first provided with a bead having a wider upper portion and a narrower lower portion, by folding said sheet member along a plurality of mutually parallel folding lines, said bead being thereupon introduced into a groove in said suspension or..stiffening member, characterised in that at least some of said folding lines are made by punching in said sheet material a plurality of elongated openings or slots leaving between each two adjacent slots a relatively long unpunched portion thereby obtaining a perforated folding line being easy to fold but difficult to tear, said folding lines being located close to each other to form there between adjacent narrow sections of the sheet material extending from one edge to another of the sheet material member, folding the sheet member along said folding lines to obtain a bead which in cross section is substantially form-persistent (i.e., difficult to bend) and finally sliding the bead thus obtained longitudinally into a groove in said suspension or stiffening member.

2. A method as claimed in claim 1, characterised in that at least one folding line is made less resistent against folding than the other lines by punching larger slots in said folding line than in the remaining folding lines.

3. A method as claimed in claim 1, characterised in that at least one of the perforated folding lines is made with a ratio length of punched slot to length of unpunched portion which differs from the corresponding ratio for the other perforated lines.

4. A method as claimed in claim 1, characterised in that the folding lines are provided near the ends of the sheet member. I

S. A method as claimed in claim 1, characterised in that the folding lines are located at such distances from each other that a bead in the shape of a triangle may be generated at least one side of said triangle comprising two superimposed folded portions of said sheet material.

6. A method as claimed in claim 1, characterised in that the width of the sections forming the bead being less than 30 times the thickness of the sheet material.

7. A method as claimed in claim 1, characterised in that at least one of the folding lines is punched such that at each end thereof there is a relatively long unpunched portion.

* i i i 

1. A method for obtaining a connection between a sheet member, made from a relatively stiff material such as cardboard or the like, and a suspension or stiffening member, said sheet member being first provided with a bead having a wider upper portion and a narrower lower portion, by folding said sheet member along a plurality of mutually parallel folding lines, said bead being thereupon introduced into a groove in said suspension or stiffening member, characterised in that at least some of said folding lines are made by punching in said sheet material a plurality of elongated openings or slots leaving between each two adjacent slots a relatively long unpunched portion thereby obtaining a perforated folding line being easy to fold but difficult to tear, said folding lines being located close to each other to form there between adjacent narrow sections of the sheet material extending from one edge to another of the sheet material member, folding the sheet member along said folding lines to obtain a bead which in cross section is substantially formpersistent (i.e., difficult to bend) and finally sliding the bead thus obtained longitudinally into a groove in said suspension or stiffening member.
 2. A method as claimed in claim 1, characterised in that at least one folding line is made less resistent against folding than the other lines by punching larger slots in said folding line than in the remaining folding lines.
 3. A method as claimed in claim 1, characterised in that at least one of the perforated folding lines is made with a ratio length of punched slot to length of unpunched portion which differs from the corresponding ratio for the other perforated lines.
 4. A method as claimed in claim 1, characterised in that the folding lines are provided near the ends of the sheet member.
 5. A method as claimed in claim 1, characterised in that the folding lines are located at such distances from each other that a bead in the shape of a triangle may be generated at least one side of said triangle comprising two superimposed folded portions of said sheet material.
 6. A method as claimed in claim 1, characterised in that the width of the sections forming the bead being less than 30 times the thickness of the sheet material.
 7. A method as claimed in claim 1, characterised in that at least one of the folding lines is punched such that at each end thereof there is a relatively long unpunched portion. 